1. Field of the Invention
The present invention relates to methods and systems for ensuring the atomicity of an atomic data transfer over one or more system buses of a computer system. In particular, the present invention relates to methods and systems for ensuring the atomicity of an atomic data transfer over a first system bus of a dual bus computer system which has two or more central processing units (CPUs), without interfering with bus activity on the second system bus.
2. Description of Related Technology
The use of semaphores in a computer system requires the atomic execution of a sequence of instructions, that is, execution as single, uninterruptible operations. An example of an atomic operation is a read-modify-write operation.
In a computer system having two or more CPUs, the atomicity of an atomic data transfer from a CPU to a memory interleave must be ensured to protect the integrity of transferred data and thus ensure proper operation of the overall computer system. The prior art solution to this problem was, and is, to lock all the system buses, thereby preventing all bus activity other than the atomic data transfer, for the duration of the atomic data transfer. This solution degrades performance by effectively transforming the multiprocessor system into a uniprocessor system for the duration of the atomic data transfer.